类中运算符重载_python黑马程序员

(13) 2024-06-04 13:01:01

目录

P121类和对象-C++运算符重载-加号运算符重载

P122类和对象-C++运算符重载-左移运算符重载

P123类和对象-C++运算符重载-递增运算符重载

P124类和对象-C++运算符重载-赋值运算符重载

P125类和对象-C++运算符重载-关系运算符重载

P126类和对象-C++运算符重载-函数调用运算符重载


运算符重载概念:对已有的运算符重新进行定义,赋予其另一种功能,以适应不同的数据类型

P121类和对象-C++运算符重载-加号运算符重载

 作用:实现两个自定义数据类型相加的运算

1、成员函数重载+号

示例:

using namespace std;
#include<iostream>
#include<string>

class Person {
public:
	int m_A;
	int m_B;
	//1、通过自己写成员函数,实现两个对象相加属性后返回新对象
	Person operator+(Person& p) {
		Person temp;
		temp.m_A = this->m_A + p.m_A;
		temp.m_B = this->m_B + p.m_B;
		return temp;
	}
};

void test01() {
	Person p1;
	p1.m_A = 10;
	p1.m_B = 10;
	Person p2;
	p2.m_A = 10;
	p2.m_B = 10;

	Person p3 = p1 + p2;//成员函数重载+号本质调用:Person p3=p1.operator+(p2);
	cout << "p3.m_A = " << p3.m_A << endl;
	cout << "p3.m_B = " << p3.m_B << endl;
}
int main()
{
	test01();
	system("pause");
	return 0;
}

结果:

类中运算符重载_python黑马程序员 (https://mushiming.com/)  第1张

2、全局函数重载+号

示例:

using namespace std;
#include<iostream>
#include<string>

class Person {
public:
	int m_A;
	int m_B;
};

Person operator+(Person& a, Person& b) {
	Person temp;
	temp.m_A = a.m_A + b.m_A;
	temp.m_B = a.m_B + b.m_B;
	return temp;
}
void test01() {
	Person p1;
	p1.m_A = 10;
	p1.m_B = 10;
	Person p2;
	p2.m_A = 10;
	p2.m_B = 10;

	Person p3 = p1 + p2;//全局函数重载+号本质调用:Person p3 = operator+(p1,p2)
	cout << "p3.m_A = " << p3.m_A << endl;
	cout << "p3.m_B = " << p3.m_B << endl;
}
int main()
{
	test01();
	system("pause");
	return 0;
}

结果:

类中运算符重载_python黑马程序员 (https://mushiming.com/)  第1张

3、运算符重载也可以发生函数重载

using namespace std;
#include<iostream>
#include<string>

class Person {
public:
	int m_A;
	int m_B;
	//1、通过自己写成员函数,实现两个对象相加属性后返回新对象
	/*Person operator+(Person& p) {
		Person temp;
		temp.m_A = this->m_A + p.m_A;
		temp.m_B = this->m_B + p.m_B;
		return temp;
	}*/
};

Person operator+(Person& a, Person& b) {
	Person temp;
	temp.m_A = a.m_A + b.m_A;
	temp.m_B = a.m_B + b.m_B;
	return temp;
}
//函数重载版本
Person operator+(Person& p1, int num) {
	Person temp;
	temp.m_A = p1.m_A + num;
	temp.m_B = p1.m_B + num;
	return temp;
}
void test01() {
	Person p1;
	p1.m_A = 10;
	p1.m_B = 10;
	Person p2;
	p2.m_A = 10;
	p2.m_B = 10;

	Person p3 = p1 + p2;//成员函数重载+号本质调用:Person p3=p1.operator+(p2);
	                    //全局函数重载+号本质调用:Person p3 = operator+(p1,p2)
	cout << "p3.m_A = " << p3.m_A << endl;
	cout << "p3.m_B = " << p3.m_B << endl;

	Person p4 = p1 + 20;
	cout << "p4.m_A = " << p4.m_A << endl;
	cout << "p4.m_B = " << p4.m_B << endl;
}
int main()
{
	test01();
	system("pause");
	return 0;
}

结果:

类中运算符重载_python黑马程序员 (https://mushiming.com/)  第3张

总结1:对于内置的数据类型的表达式的的运算符是不可能改变的

总结2:不要滥用运算符重载

P122类和对象-C++运算符重载-左移运算符重载

作用:可以输出自定义数据类型

using namespace std;
#include<iostream>

class Person {
public:
	int m_A;
	int m_B;
	//不会利用成员函数重载左移运算符,因为无法实现cout在左侧
	
};
//只能利用全局函数重载左移运算符
void operator<<(ostream &cout, Person &p) //本质operator<<(cout,p)简化为cout<<p
{
	cout << "m_A = " << p.m_A << " m_B = " << p.m_B << endl;
}
void test01() {
	Person p1;
	p1.m_A = 10;
	p1.m_B = 10;
	cout << p1 ;
}
int main()
{
	test01();
	system("pause");
	return 0;
}

P123类和对象-C++运算符重载-递增运算符重载

作用: 通过重载递增运算符,实现自己的整型数据

示例:

using namespace std;
#include<iostream>

//自定义整型
class MyInteger {
	friend ostream& operator<<(ostream& out, MyInteger myint);
public:
	MyInteger() {
		m_num = 0;
	}
	//重载前置++运算符 返回引用是为了一直对一个数据进行递增操作
	MyInteger& operator++() {
		//先++
		m_num++;
		//后返回
		return *this;
	}
	//重载后置++运算符
	//int代表占位参数,可以用于区分前置和后置递增
	MyInteger operator++(int) {
		//先返回
		MyInteger temp = *this; //记录当前本身的值,然后让本身的值加1,但是返回的是以前的值,达到先返回后++;
		m_num++;
		return temp;
	}
private:
	int m_num;
};
ostream& operator<<(ostream& out, MyInteger myint) {
	out << myint.m_num;
	return out;
}
//前置++ 先++ 再返回
void test01() {
	MyInteger myInt;
	cout << ++myInt << endl;
	cout << myInt << endl;
}
//后置++ 先返回 再++
void test02() {

	MyInteger myInt;
	cout << myInt++ << endl;
	cout << myInt << endl;
}
int main()
{
	test02();
	system("pause");
	return 0;
}

P124类和对象-C++运算符重载-赋值运算符重载

c++编译器至少给一个类添加4个函数

  1. 默认构造函数(无参,函数体为空)

  2. 默认析构函数(无参,函数体为空)

  3. 默认拷贝构造函数,对属性进行值拷贝

  4. 赋值运算符 operator=, 对属性进行值拷贝

如果类中有属性指向堆区,做赋值操作时也会出现深浅拷贝问题

示例:

class Person
{
public:

	Person(int age)
	{
		//将年龄数据开辟到堆区
		m_Age = new int(age);
	}

	//重载赋值运算符 
	Person& operator=(Person &p)
	{
		if (m_Age != NULL)
		{
			delete m_Age;
			m_Age = NULL;
		}
		//编译器提供的代码是浅拷贝
		//m_Age = p.m_Age;

		//提供深拷贝 解决浅拷贝的问题
		m_Age = new int(*p.m_Age);

		//返回自身
		return *this;
	}


	~Person()
	{
		if (m_Age != NULL)
		{
			delete m_Age;
			m_Age = NULL;
		}
	}

	//年龄的指针
	int *m_Age;

};


void test01()
{
	Person p1(18);

	Person p2(20);

	Person p3(30);

	p3 = p2 = p1; //赋值操作

	cout << "p1的年龄为:" << *p1.m_Age << endl;

	cout << "p2的年龄为:" << *p2.m_Age << endl;

	cout << "p3的年龄为:" << *p3.m_Age << endl;
}

int main() {

	test01();

	//int a = 10;
	//int b = 20;
	//int c = 30;

	//c = b = a;
	//cout << "a = " << a << endl;
	//cout << "b = " << b << endl;
	//cout << "c = " << c << endl;

	system("pause");

	return 0;
}

P125类和对象-C++运算符重载-关系运算符重载

作用:重载关系运算符,可以让两个自定义类型对象进行对比操作

示例:

class Person
{
public:
	Person(string name, int age)
	{
		this->m_Name = name;
		this->m_Age = age;
	};

	bool operator==(Person & p)
	{
		if (this->m_Name == p.m_Name && this->m_Age == p.m_Age)
		{
			return true;
		}
		else
		{
			return false;
		}
	}

	bool operator!=(Person & p)
	{
		if (this->m_Name == p.m_Name && this->m_Age == p.m_Age)
		{
			return false;
		}
		else
		{
			return true;
		}
	}

	string m_Name;
	int m_Age;
};

void test01()
{
	//int a = 0;
	//int b = 0;

	Person a("孙悟空", 18);
	Person b("孙悟空", 18);

	if (a == b)
	{
		cout << "a和b相等" << endl;
	}
	else
	{
		cout << "a和b不相等" << endl;
	}

	if (a != b)
	{
		cout << "a和b不相等" << endl;
	}
	else
	{
		cout << "a和b相等" << endl;
	}
}


int main() {

	test01();

	system("pause");

	return 0;
}

P126类和对象-C++运算符重载-函数调用运算符重载

  • 函数调用运算符 () 也可以重载

  • 由于重载后使用的方式非常像函数的调用,因此称为仿函数

  • 仿函数没有固定写法,非常灵活

示例:

class MyPrint
{
public:
	void operator()(string text)
	{
		cout << text << endl;
	}

};
void test01()
{
	//重载的()操作符 也称为仿函数
	MyPrint myFunc;
	myFunc("hello world");
}


class MyAdd
{
public:
	int operator()(int v1, int v2)
	{
		return v1 + v2;
	}
};

void test02()
{
	MyAdd add;
	int ret = add(10, 10);
	cout << "ret = " << ret << endl;

	//匿名对象调用  
	cout << "MyAdd()(100,100) = " << MyAdd()(100, 100) << endl;
}

int main() {

	test01();
	test02();

	system("pause");

	return 0;
}

THE END

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